The London auctioneers Bonhams are under pressure to withdraw several of the prized pieces from its forthcoming antiquities sale after a senior Italian politician raised questions over their provenance.

Francesco Rutelli, the former Italian Minister for Culture and Deputy Prime Minister, told the Italian Parliament he had believed that some of the antiquities to be auctioned in London next week had been exported illegally from Italy.

In an "urgent question" to Sandro Bondi, his successor as Culture Minister, he accused the centre-right Berlusconi Government, which took power in May, of failing to take action over the illegal export of archaeological treasures.